iknowtax.com - UK Tax and NI calculator

It provides an online Salary Tax and NI calculator tool free to use and explains the rates and how Tax and NI is calculated. It allows anyone to enter their salary and see their take home pay after income tax and national insurance contribution deducted. It displays the calculations in yearly, monthly, weekly and hourly. It also lets the user enter how many hours a week they work for it to display their hourly rate accurately.

It also provides income tax, personal allowance and national insurance rates in an easy to understand manner for anyone who is very unfamiliar about understanding the tax rates.

The site explains and teaches absolutely anyone from scratch who does not have any idea about how is Tax calculated, understanding the rates and how to apply the rates.

It also provides examples of tax calculation.

Tax and NI Calculator tool features

Error creating thumbnail: convert: no decode delegate for this image format `/tmp/s3thumb-mRGOQg' @ error/constitute.c/ReadImage/544.
convert: no images defined `/tmp/s3thumb-mRGOQg' @ error/convert.c/ConvertImageCommand/3046.

The tool is very easy to use, here are the features:

  • Calculates as you type
  • Enter salary as yearly, monthly, weekly or hourly
  • Enter number of hours work in a week
  • Option to select age, as different rates apply for the calculations
  • Option to select if Blind, receive Married Couples allowance, or exclude to calculate NI
  • Shows breakdown clearly in a table
  • Compare the ‘Take home pay’ to previous tax year

Learn from scratch

The unique thing about this website is the explanation of how Tax and NI is applied and calculated to anyone who has no knowledge about this at all. It is an educational website.

After visiting this website one can feel confident in explaining the tax rates and calculations to others, and will be able to eliminate many tax myths and confusions out there.

To make things simple the rates are in separate table with explanation for Personal Allowance, Income Tax, and National Insurance. This is made easy and clear to understand compared to the information on HMRC website.

Why did the owner make this website

"Hi, I'm Kashem. I have made this website because when I wanted to understand how the tax and was deducted from my payslip it was very difficult to find out. I asked people but everyone gave different answers or they did not know. I turned to the internet for help but it was difficult to find answers. It required me to do some intensive searching, thinking and asking around many people to put bits of information together for someone who knew nothing about tax rates and how it’s calculated. After all this I realised how little many people knew about tax rates and how it is calculated and the difficulty in learning by anyone who has no knowledge. My attempt to solve this problem was to create iknowtax.com and providing the information as the first stop/starting point for anyone wanting to understand tax rates and calculations. I believe this website helps many people each day, and I can’t wait until the day comes when no person is unfamiliar about tax rates and calculations. There shall no more be confusions or any myths like getting a higher pay will result you in taking home less pay compared to your previous salary; -which is not true"

Feedback from users

Hands down, this is a excellent breakdown to help people out especially if they are unfamiliar with UK tax, maybe the HMRC website should follow suit! Trainee Accountant

This is a very useful website. The tax calculations have been explained in plain English. Well Done!


Absolutely wonderful. I got ALL the answers I was looking for. Actually feel 'competent' enough to explain it to friends and family myself. Thank you for all your effort and work to put this together. true citizenship spirit!!!!!!


at last i've found proper info, thanks